WATER LAB REVIEW
Rate of Osmosis with Three Different Gradients
7
6
Weight in gms
5
4
30 Percent
3
Percent
15
0 Percent
2
1
0
0
10
20
30
40
-1
Time in Minutes
In this experiment we compared the rate of osmosis with three concentrations of sucrose.  What is osmosis?  How does concentration gradient affect the rate of osmosis?  Why don’t the sugar molecules move out of the osmometers?  If an osmometer has 25% sucrose and it is in a solution of 35% sucrose, will the osmometer shrink or expand?  Hint: Convert the sucrose concentrations to water concentrations. Starting Ending Change in Temperature °F
Temperature °F
Temperature °F
Water
o 82
Mineral Oil
o 105
o 82
o 23
o 129
o 47
 Given that equal heat is applied, which heats up faster? Water or mineral oil?  Why?  What is this called? These are water molecules.  What atom is represented by the white?  What atom is represented by the red?  What is the name of the chemical bond that holds the white atoms to the red atoms WITHIN the water molecule?  What is the name of the attractive bond that is found BETWEEN water molecules? Be sure you can draw four water molecules hydrogen bonded to one another. Show and Label:  Charges  Covalent Bonds (within molecules)  Hydrogen Bonds (between molecules)  Hydrogen and Oxygen atoms  Why does water rise in a glass tube?  Why does water rise higher in the narrower tubes?  What is this process called?  Why doesn’t this water strider sink in the water?  What is this characteristic of water called?  What do you think would happen to the water strider if we added a drop of detergent?  Why? Consider ice, warm water, and really cold water (4 o C).  Which is the most dense (heaviest)?  Which is the least dense (lightest)? Explain why. Why is the stream of water attracted to the charged rod? What do we mean when we say a molecule is polar? What do we mean when we say a molecule is non‐polar? Would a non‐polar substance be attracted to the rod? Read the pH for the strips labeled A – E. 
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

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Which strip has the highest concentration of H+? Which strip has the lowest concentration of H+? Which are considered acidic? Which are considered basic? What is the pH of a neutral substance?